Keyway Calculations
Video
Factors that affect keyway calculation include:
  • Loading: Tension, bending, or torsion
  • Key: Loaded with or without the key inserted in the keyway
  • Stress: At the keyway end or in the prismatic part
  • Material: Shaft material and key material
  • Safety: Factor of safety 
Level 2 Fitting and Turning, only rectangular keys had to be calculated.
 
Rectangular sunk key
The usual proportions of this key are : Width of key, w = d / 4 ; and thickness of key, t = 2w / 3 = d / 6 where d = Diameter of the shaft or diameter of the hole in the hub.
 
Example:
A shaft with a diameter of 36 mm must be provided with a key and keyway to secure a pulley to it.
Calculate the height (h) and width (w) of the key.
 
h   = D/6
     = 36/6
     = 6 mm

w  = D/4
     = 36/4
     = 9 mm